Transport in humans Flashcards
Diffusion
Net movement of particles from an area of high concentration to an area of low concentration
Describe the movement of molecules
Constant and random
What is diffusion responsible for?
The movement of substances in living things
Give two examples of diffusion
Small molecules pass through cell membranes to cytoplasm
Diffusion moves oxygen and glucose into cells for respiration and removes carbon dioxide and other wastes
What are four factors affecting the rate of diffusion?
Surface area
Temperature
Volume
Concentration gradient
As cells and organisms get bigger, what increases more?
Volume
What affect does SA:V ratio have on diffusion?
Increased volume = decreased surface area = slower rate of diffusion
Name two specialised exchange surfaces to maximise diffusion in humans
Alveoli in the lungs
Villi in the small intestine
What is the function of the circulatory system?
To transport substances around the body e.g oxygen and nutrients to cells and waste products from cells to lungs and kidneys
What three things does the circulatory system require to do its job?
Liquid to transport substances in - the blood
A pump - the heart
A series of pipes to move the blood efficiently - the blood vessels
What is double circulation?
The heart pumps the blood twice sending it through two different circulatory circuits
What is the pulmonary circulation?
Deoxygenated blood is pumped to the lungs where oxygen is gained and carbon dioxide is lost. It is then pumped back to the heart
What is the systemic circulation?
Oxygenated blood pumped round the body where the cells absorb oxygen and release carbon dioxide.
What artery goes to the liver?
Hepatic artery
What vein leaves the liver?
Hepatic vein
What artery goes to the kidneys?
Renal artery
What vein leaves the kidneys?
Renal vein
What is the vena cava?
Main vein carrying deoxygenated blood back to the heart.
What is the aorta?
Main artery carrying oxygenated blood away from the heart
Why is a double circulatory system more efficient than a single?
By pumping blood twice, higher pressures can be maintained and so blood can move further and faster
What is metabolic rate?
The rate of chemical reactions in the body
What is blood?
A complex tissue consisting of a liquid component (plasma), cell fragments (platelets) and two types of cells (red and white blood cells)
What is plasma?
A straw coloured liquid, mainly water, which transports the blood cells and carries dissolved nutrients (glucose and amino acids), dissolved waste products (urea and carbon dioxide), hormones (protein and fats). It also distributes heat energy around the body
What are platelets?
Small cell fragments which help to form clots preventing blood loss and infection
What is the function of white blood cells?
To destroy pathogens which infect our body. They are an essential part of the immune system
Function of red blood cells
To transport oxygen
About red blood cells
Highly specialised cells
Made in the bone marrow
Only live for around 100 days
Contain haemoglobin
What shape are red blood cells?
Biconcave. Increases surface area: volume ratio and decreases distance to centre of cell, allowing for efficient diffusion of oxygen in and out.
No nucleus means more haemoglobin can be packed in so more oxygen can be transported
What is haemoglobin?
An iron-containing protein
How does haemoglobin work?
When oxygen concentration is high (in lungs)
It combines with oxygen to form oxyhaemoglobin
When oxygen concentration decreases (in respiring tissues) oxyhaemoglobin releases the oxygen.
What is the function of the heart?
To pump blood around the body
Where is the heart?
In the centre of the thorax partially surrounded by the lungs and protected by the rib cage
What is the heart made of?
Cardiac muscle
What is the average resting heart rate?
70
What does the right side of the heart do?
Pumps deoxygenated blood to the lungs
What does the left side of the heart do?
Pump oxygenated blood to the rest of the body
Structure of the heart?
Four chambers (two atria at the top, two ventricles at the bottom)
Describe atrium walls
Thin muscular
Describe ventricle walls
Thick muscular (septum) Left ventricle wall much thicker than right due to higher blood pressure
Name the two circulatory systems
Pulmonary (lungs) and systemic (rest of body)
What is the vena cava?
Blood vessel bringing deoxygenated blood into the heart
What are the pulmonary veins?
Vessels carrying oxygenated blood from lungs to heart
What do veins carry?
Deoxygenated blood except pulmonary vein
What do arteries carry?
Oxygenated blood except pulmonary artery
Name the valves in the heart
Semilunar, bicuspid and tricuspid
What do tricuspid and bicuspid valves do?
Stop blood from flowing back into the atria
What do semilunar valves do?
Prevent flow of blood back into the heart
What causes heart valves to open and close?
Changes in blood pressure
Structure of an artery
Thick outer wall
Thick layer of muscles and elastic fibres
Small lumen to allow expansion under pressure
What helps blood flow in arteries?
A thin layer of endothelial cells
Structure of veins
Fairly thin outer wall
Thin layer of muscle and elastic fibres
Large lumen, enables blood to flow easily
Contain one way pocket valves to prevent back flow of blood
What are capillaries?
Very thin blood vessels with single layer cell wall for easy diffusion
What is heart rate?
Number of beats per minute
What is stroke volume?
Volume of blood pumped with each heartbeat
Why does heart rate increase with exercise?
To increase supply of oxygen
To provide extra glucose
To remove excess heat energy
To remove carbon dioxide
What is fight or flight?
Increase in oxygen and glucose to the muscles when angry or afraid triggered by adrenaline
What is the medulla?
Part of the brain that controls heart rate
